A Balanced Diet
Friday, 8 May 2026
10:57 PM
Components of a healthy, balanced diet:
A balanced diet consists of all of the food groups in the correct proportions
The necessary key food groups are:
○ Carbohydrates
○ Proteins
○ Lipids
○ Dietary fibre
○ Vitamins
○ Minerals (mineral ions)
○ Water
There are a number of major components to a balanced diet:
1. Carbohydrates should make up 45%-65% of the diet.
○ Carbohydrates include breads, grains and pasta.
2. Proteins should make up 10%-35% of the diet.
○ Proteins include meats, fish and eggs.
3. Lipids should make up 20%-35% of the diet.
○ Lipids include fats and oils.
4. There should be a number of vitamins and minerals in the diet.
○ Vitamins and minerals are present in the other major food groups.
Energy requirements:
5. At least 2 litres of water should be consumed per day.
Different people require different amounts of energy:
Athletes have a high requirement for energy.
Malnutrition
- Having an unbalanced diet can lead to malnutrition
- Malnutrition can cause a variety of different health problems in humans
- The more exercise an individual does, the more calories are burned.
Children have a high requirement for energy.
- Lots of energy is required to build mass.
Pregnant women have a high requirement for energy
Causes & Effects of Malnutrition:
- Lots of energy is required to support the growth of a foetus.
The nutritional requirements for individuals will vary throughout their lifetime
An individual will still require the same key food groups, but in different quantities depending on a
number of factors such as age, height, sex, activity levels, pregnancy and breastfeeding
- The amount of energy that young people need increases towards adulthood as this energy is
needed for growth. Children need a higher proportion of protein in their diet than adults as this is
required for growth
- Energy needs of adults decrease as they age
- The more active, the more energy required for movement as muscles are contracting more and
respiring faster
- During pregnancy, energy requirements increase as energy is needed to support the growth of
the developing fetus, as well as the larger mass that the mother needs to carry around. Extra
calcium and iron are also needed in the diet to help build the bones, teeth, and blood of the fetus
- For breastfeeding mothers, energy requirements increase and extra calcium is still needed to
make high-quality breast milk
Sources & Functions of Dietary Elements
There are seven main food groups. These are:
- Carbohydrates
- Proteins
- Lipids
- Water
- Dietary Fibre
- Vitamins
- Minerals
Carbohydrates:
- Carbohydrates are required for energy.
Protein:
- Proteins are required for the growth and repair of cells.
○ Carbohydrates are easily broken down into glucose.
○ Proteins contain amino acids.
○ Glucose is then respired to release energy.
○ Amino acids are required to build new structural and functional
proteins.
- Function: source of energy
- Sources: bread, cereals, pasta, rice, potatoes
Lipids (fats & oils):
- Lipids are required for long term storage, insulation and protection.
○ Lipids contain fatty acids and glycerol.
- Function: growth and repair
○ These are broken down when no carbohydrates remain in the
body.
○ Lipids also protect organs and insulate the body from the cold.
- Sources: meat, fish, eggs, pulses, nuts
- Function: insulation and energy storage
- Sources: butter, oil, nuts, avocado
Water:
Dietary Fibre:
- Around 60% of the body is made up of water.
- Dietary fibre consists of cellulose.
- Water is a medium for chemical reactions.
- Water is also a transport mechanism.
○ Blood is primarily composed of water.
- Water is often found in large quantities in food.
○ Cucumbers consist of 96% water.
- Water is vital for a number of cellular processes. Around 2 litres of water are required
every day.
- Function: needed for chemical reactions to take place in the body
○ Dietary fibre is sometimes referred to as roughage
- Cellulose is found in plant cell walls.
- Fruits and vegetables are a good source of dietary fibre.
- Dietary fibre is not digested by the body.
○ Dietary fibre provides bulk for the muscles of the digestive
system to push against.
- Dietary fibre helps to keep the gut healthy.
○ Dietary fibre also helps to avoid constipation.
Water:
Dietary Fibre:
- Around 60% of the body is made up of water.
- Dietary fibre consists of cellulose.
- Water is a medium for chemical reactions.
- Water is also a transport mechanism.
○ Blood is primarily composed of water.
- Water is often found in large quantities in food.
○ Cucumbers consist of 96% water.
- Water is vital for a number of cellular processes. Around 2 litres of water are required
every day.
- Function: needed for chemical reactions to take place in the body
- Sources: water, juice, milk, fruits and vegetables
○ Dietary fibre is sometimes referred to as roughage
- Cellulose is found in plant cell walls.
- Fruits and vegetables are a good source of dietary fibre.
- Dietary fibre is not digested by the body.
○ Dietary fibre provides bulk for the muscles of the digestive
system to push against.
- Dietary fibre helps to keep the gut healthy.
○ Dietary fibre also helps to avoid constipation.
- Dietary fibre helps to aid digestion and keep the gut healthy.
- Function: provides bulk (roughage) for the intestine to push food
through it
- Sources: vegetables, whole grains
Vitamins:
Minerals:
- Vitamins are micronutrients the body needs to function correctly.
- Minerals are micronutrients the body needs to function correctly
○ Vitamins cannot be synthesised by the body.
- Vitamin A is important for good vision.
○ Vitamin A makes a light-sensitive chemical in the eye called retinol.
○ Vitamin A deficiency can lead to night blindness.
- One good source of vitamin A are carrots.
- Vitamin C is important for healthy skin.
○ Vitamin C is involved in the manufacture of a connective tissue called collagen.
- Calcium is important for the maintenance of healthy teeth and bones.
- Calcium is commonly found in dairy products such as milk and cheese.
- Iron is needed to form haemoglobin.
○ Haemoglobin is a protein found in red blood cells which carry oxygen (O2) around the
body
- Iron is found in red meat, eggs and spinach.
○ A deficiency in iron is called anemia.
○ Vitamin C deficiency can lead to scurvy.
- Function: needed in small quantities to maintain health
- One good source of vitamin C are citrus fruits
- Sources: fruits and vegetables, meats, dairy products
- Vitamin D is important for healthy bones.
○ Vitamin D helps the body absorb calcium.
Examples:
○ Vitamin D deficiency can lead to rickets
- Calcium is needed for strong teeth and bones and is involved in the clotting of blood
- One good source of vitamin D is sunlight.
○ Calcium is found in milk, cheese, and eggs
- Function: needed in small quantities to maintain health
○ A deficiency can lead later in life to osteoporosis, a condition in which the bones
become less dense and more fragile, making them more likely to break (fracture)
- Sources: fruits and vegetables, meats, dairy products
Examples:
- Vitamin D helps the body to absorb calcium and is required for strong bones and
teeth
○ Vitamin D can be found in oily fish and dairy products, and is also made naturally
by the body in sunlight
○ A severe deficiency of vitamin D can lead to rickets, a condition in children
characterised by poor bone development
○ In children, a vitamin D deficiency can prevent the body from effectively absorbing
calcium, causing rickets.
○ Rickets softens the bones, meaning they may grow in a misshapen way.
○ UV light from the sun causes a chemical reaction on the surface of the skin,
creating vitamin D.
- Vitamin C forms an essential part of collagen protein, which makes up the skin, hair,
gums, and bones
○ A deficiency can cause scurvy.
§ A disease which is associated with a general worsening of the skin, hair and
gums.
○ It is found in citrus fruits like orange and some green vegetables
- Vitamin A is needed to make the pigment in the retina for vision
○ It can be found in meat, liver, dairy, leafy green vegetables like spinach, and eggs
○ Carrots are a good source of Vitamin A
- Iron is needed to make haemoglobin, the pigment in red blood cells that helps to carry
oxygen
○ It can be found in red meat, liver, leafy green vegetables, and spinach